Thermally actuated ink jet printing mechanism having a series of thermal actuator units

ABSTRACT

An inkjet nozzle arrangement is disclosed including a nozzle chamber having an fluid ejection nozzle in one surface of the chamber; a paddle vane located within the chamber, the paddle vane being adapted to be actuated by an actuator device for the ejection of fluid out of the chamber via the fluid ejection nozzle; and a thermal actuator device located externally of the nozzle chamber and attached to the paddle vane the thermal actuator device including a plurality of separate spaced apart elongated thermal actuator units. Preferably, the thermal actuator units are interconnected at a first end to a substrate and at a second end to a rigid strut member. The rigid strut member can, in turn, be interconnected to a lever arm having one end attached to the paddle vane. The thermal actuator units can operate upon conductive heating along a conductive trace and the conductive heating includes the generation of a substantial portion of the heat in the area adjacent the first end. The conductive heating trace can include a thinned cross-section adjacent the first end. The heating layers of the thermal actuator units can include substantially either a copper nickel alloy or titanium nitride. The paddle can be constructed from a similar conductive material to portions of the thermal actuator units however it is conductively insulated therefrom.

CROSS REFERENCES TO RELATED APPLICATIONS

[0001] The following Australian provisional patent applications arehereby incorporated by cross-reference. For the purposes of location andidentification, US patent applications identified by their US patentapplication serial numbers (USSN) are listed alongside the Australianapplications from which the US patent applications claim the right ofpriority. US PATENT/PATENT APPLICATION CROSS-REFERENCED (CLAIMING RIGHTOF AUSTRALIAN PRIORITY FROM PROVISIONAL AUSTRALIAN PATENT PROVISIONALDOCKET APPLICATION NO. APPLICATION) NO. PO7991 09/113,060 ART01 PO850509/113,070 ART02 PO7988 09/113,073 ART03 PO9395 09/112,748 ART04 PO801709/112,747 ART06 PO8014 09/112,776 ART07 PO8025 09/112,750 ART08 PO803209/112,746 ART09 PO7999 09/112,743 ART10 PO7998 09/112,742 ART11 PO803109/112,741 ART12 PO8030 09/112,740 ART13 PO7997 09/112,739 ART15 PO797909/113,053 ART16 PO8015 09/112,738 ART17 PO7978 09/113,067 ART18 PO798209/113,063 ART19 PO7989 09/113,069 ART20 PO8019 09/112,744 ART21 PO798009/113,058 ART22 PO8018 09/112,777 ART24 PO7938 09/113,224 ART25 PO801609/112,804 ART26 PO8024 09/112,805 ART27 PO7940 09/113,072 ART28 PO793909/112,785 ART29 PO8501 09/112,797 ART30 PO8500 09/112,796 ART31 PO798709/113,071 ART32 PO8022 09/112,824 ART33 PO8497 09/113,090 ART34 PO802009/112,823 ART38 PO8023 09/113,222 ART39 PO8504 09/112,786 ART42 PO800009/113,051 ART43 PO7977 09/112,782 ART44 PO7934 09/113,056 ART45 PO799009/113,059 ART46 PO8499 09/113,091 ART47 PO8502 09/112,753 ART48 PO798109/113,055 ART50 PO7986 09/113,057 ART51 PO7983 09/113,054 ART52 PO802609/112,752 ART53 PO8027 09/112,759 ART54 PO8028 09/112,757 ART56 PO939409/112,758 ART57 PO9396 09/113,107 ART58 PO9397 09/112,829 ART59 PO939809/112,792 ART60 PO9399 6,106,147 ART61 PO9400 09/112,790 ART62 PO940109/112,789 ART63 PO9402 09/112,788 ART64 PO9403 09/112,795 ART65 PO940509/112,749 ART66 PPO959 09/112,784 ART68 PP1397 09/112,783 ART69 PP237009/112,781 DOT01 PP2371 09/113,052 DOT02 PO8003 09/112,834 Fluid01PO8005 09/113,103 Fluid02 PO9404 09/113,101 Fluid03 PO8066 09/112,751IJ01 PO8072 09/112,787 IJ02 PO8040 09/112,802 IJ03 PO8071 09/112,803IJ04 PO8047 09/113,097 IJ05 PO8035 09/113,099 IJ06 PO8044 09/113,084IJ07 PO8063 09/113,066 IJ08 PO8057 09/112,778 IJ09 PO8056 09/112,779IJ10 PO8069 09/113,077 IJ11 PO8049 09/113,061 IJ12 PO8036 09/112,818IJ13 PO8048 09/112,816 IJ14 PO8070 09/112,772 IJ15 PO8067 09/112,819IJ16 PO8001 09/112,815 IJ17 PO8038 09/113,096 IJ18 PO8033 09/113,068IJ19 PO8002 09/113,095 IJ20 PO8068 09/112,808 IJ21 PO8062 09/112,809IJ22 PO8034 09/112,780 IJ23 PO8039 09/113,083 IJ24 PO8041 09/113,121IJ25 PO8004 09/113,122 IJ26 PO8037 09/112,793 IJ27 PO8043 09/112,794IJ28 PO8042 09/113,128 IJ29 PO8064 09/113,127 IJ30 PO9389 09/112,756IJ31 PO9391 09/112,755 IJ32 PPO888 09/112,754 IJ33 PPO891 09/112,811IJ34 PPO890 09/112,812 IJ35 PPO873 09/112,813 IJ36 PPO993 09/112,814IJ37 PPO890 09/112,764 IJ38 PP1398 09/112,765 IJ39 PP2592 09/112,767IJ40 PP2593 09/112,768 IJ41 PP3991 09/112,807 IJ42 PP3987 09/112,806IJ43 PP3985 09/112,820 IJ44 PP3983 09/112,821 IJ45 PO7935 09/112,822IJM01 PO7936 09/112,825 IJM02 PO7937 09/112,826 IJM03 PO8061 09/112,827IJM04 PO8054 09/112,828 IJM05 PO8065 6,071,750 IJM06 PO8055 09/113,108IJM07 PO8053 09/113,109 IJM08 PO8078 09/113,123 IJM09 PO7933 09/113,114IJM10 PO7950 09/113,115 IJM11 PO7949 09/113,129 IJM12 PO8060 09/113,124IJM13 PO8059 09/113,125 IJM14 PO8073 09/113,126 IJM15 PO8076 09/113,119IJM16 PO8075 09/113,120 IJM17 PO8079 09/113,221 IJM18 PO8050 09/113,116IJM19 PO8052 09/113,118 IJM20 PO7948 09/113,117 IJM21 PO7951 09/113,113IJM22 PO8074 09/113,130 IJM23 PO7941 09/113,110 IJM24 PO8077 09/113,112IJM25 PO8058 09/113,087 IJM26 PO8051 09/113,074 IJM27 PO8045 6,111,754IJM28 PO7952 09/113,088 IJM29 PO8046 09/112,771 IJM30 PO9390 09/112,769IJM31 PO9392 09/112,770 IJM32 PPO889 09/112,798 IJM35 PPO887 09/112,801IJM36 PPO882 09/112,800 IJM37 PPO874 09/112,799 IJM38 PP1396 09/113,098IJM39 PP3989 09/112,833 IJM40 PP2591 09/112,832 IJM41 PP3990 09/112,831IJM42 PP3986 09/112,830 IJM43 PP3984 09/112,836 IJM44 PP3982 09/112,835IJM45 PPO895 09/113,102 IR01 PPO870 09/113,106 IR02 PPO869 09/113,105IR04 PPO887 09/113,104 IR05 PPO885 09/112,810 IR06 PPO884 09/112,766IR10 PPO886 09/113,085 IR12 PPO871 09/113,086 IR13 PPO876 09/113,094IR14 PPO877 09/112,760 IR16 PPO878 09/112,773 IR17 PPO879 09/112,774IR18 PPO883 09/112,775 IR19 PPO880 09/112,745 IR20 PPO881 09/113,092IR21 PO8006 6,087,638 MEMS02 PO8007 09/113,093 MEMS03 PO8008 09/113,062MEMS04 PO8010 6,041,600 MEMS05 PO8011 09/113,082 MEMS06 PO7947 6,067,797MEMS07 PO7944 09/113,080 MEMS09 PO7946 6,044,646 MEMS10 PO939309/113,065 MEMS11 PPO875 09/113,078 MEMS12 PPO894 09/113,075 MEMS13

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.

FIELD OF THE INVENTION

[0003] The present invention relates to the field of inkjet printersand, discloses an inkjet printing system which includes a bend actuatorinterconnected into a paddle for the ejection of ink through an inkejection port. The present invention further discloses a thermallyactuated ink jet printer having a series of thermal actuator units.

BACKGROUND OF THE INVENTION

[0004] Many different types of printing have been invented, a largenumber of which are presently in use. The known forms of print have avariety of methods for marking the print media with a relevant markingmedia. Commonly used forms of printing include offset printing, laserprinting and copying devices, dot matrix type impact printers, thermalpaper printers, film recorders, thermal wax printers, dye sublimationprinters and ink jet printers both of the drop on demand and continuousflow type. Each type of printer has its own advantages and problems whenconsidering cost, speed, quality, reliability, simplicity ofconstruction and operation etc.

[0005] In recent years, the field of ink jet printing, wherein eachindividual pixel of ink is derived from one or more ink nozzles hasbecome increasingly popular primarily due to its inexpensive andversatile nature.

[0006] Many different techniques on ink jet printing have been invented.For a survey of the field, reference is made to an article by J Moore,“Non-Impact Printing: Introduction and Historical Perspective”, OutputHard Copy Devices, Editors R Dubeck and S Sherr, pages 207-220 (1988).

[0007] Ink Jet printers themselves come in many different types. Theutilization of a continuous stream of ink in ink jet printing appears todate back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hanselldiscloses a simple form of continuous stream electro-static ink jetprinting.

[0008] U.S. Pat. No. 3,596,275 by Sweet also discloses a process of acontinuous ink jet printing including the step wherein the ink jetstream is modulated by a high frequency electro-static field so as tocause drop separation. This technique is still utilized by severalmanufacturers including Elmjet and Scitex (see also U.S. Pat. No.3,373,437 by Sweet et al)

[0009] Piezoelectric ink jet printers are also one form of commonlyutilized ink jet printing device. Piezoelectric systems are disclosed byKyser et. al. in U.S. Pat. No. 3,946,398 (1970) which utilizes adiaphragm mode of operation, by Zolten in U.S. Pat. No. 3,683,212 (1970)which discloses a squeeze mode of operation of a piezoelectric crystal,Stemme in U.S. Pat. No. 3,747,120 (1972) discloses a bend mode ofpiezoelectric operation, Howkins in U.S. Pat. No. 4,459,601 discloses apiezoelectric push mode actuation of the ink jet stream and Fischbeck inU.S. Pat. No. 4,584,590 which discloses a shear mode type ofpiezoelectric transducer element.

[0010] Recently, thermal ink jet printing has become an extremelypopular form of ink jet printing. The ink jet printing techniquesinclude those disclosed by Endo et al in GB 2007162 (1979) and Vaught etal in U.S. Pat. No. 4,490,728. Both the aforementioned referencesdisclosed ink jet printing techniques that rely upon the activation ofan electrothermal actuator which results in the creation of a bubble ina constricted space, such as a nozzle, which thereby causes the ejectionof ink from an aperture connected to the confined space onto a relevantprint media. Printing devices utilizing the electro-thermal actuator aremanufactured by manufacturers such as Canon and Hewlett Packard.

[0011] As can be seen from the foregoing, many different types ofprinting technologies are available. Ideally, a printing technologyshould have a number of desirable attributes. These include inexpensiveconstruction and operation, high speed operation, safe and continuouslong term operation etc. Each technology may have its own advantages anddisadvantages in the areas of cost, speed, quality, reliability, powerusage, simplicity of construction operation, durability and consumables.

[0012] In the construction of any inkjet printing system, there are aconsiderable number of important factors which must be traded offagainst one another especially as large scale printheads areconstructed, especially those of a pagewidth type. A number of thesefactors are outlined in the following paragraphs.

[0013] Firstly, inkjet printheads are normally constructed utilizingmicro-electromechanical systems (MEMS) techniques. As such, they tend torely upon standard integrated circuit construction/fabricationtechniques of depositing planar layers on a silicon wafer and etchingcertain portions of the planar layers. Within silicon circuitfabrication technology, certain techniques are more well known thanothers. For example, the techniques associated with the creation of CMOScircuits are likely to be more readily used than those associated withthe creation of exotic circuits including ferroelectrics, galiumarsenide etc. Hence, it is desirable, in any MEMS constructions, toutilize well proven semi-conductor fabrication techniques which do notrequire any “exotic” processes or materials. Of course, a certain degreeof trade off will be undertaken in that if the advantages of using theexotic material far out weighs its disadvantages then it may becomedesirable to utilize the material anyway.

[0014] With a large ray of ink ejection nozzles, it is desirable toprovide for a highly automated form of manufacturing which results in aninexpensive production of multiple printhead devices.

[0015] Preferably, the device constructed utilizes a low amount ofenergy in the ejection of ink. The utilization of a low amount of energyis particularly important when a large pagewidth full color printhead isconstructed having a large array of individual print ejection mechanismwith each ejection mechanisms, in the worst case, being fired in a rapidsequence.

SUMMARY OF THE INVENTION

[0016] It is an object of the present invention to provide an inkejection nozzle arrangement suitable for incorporation into an inkjetprinthead arrangement for the ejection of ink on demand from a nozzlechamber in an efficient manner.

[0017] In accordance with a first aspect of the present invention, thereis provided an inkjet nozzle arrangement comprising a nozzle chamberhaving an fluid ejection port in one surface of the chamber; a paddlevane located within the chamber, the paddle vane being adapted to beactuated by an actuator for the ejection of fluid out of the chamber viathe fluid ejection port; and a thermal device located externally of thenozzle chamber and attached to the paddle vane, via an arm, the thermalactuator device including a plurality of separate spaced apart elongatethermal actuator units.

[0018] Preferably, the thermal actuator units are interconnected at afirst end to a substrate and at a second end to a rigid strut member.The rigid strut member can, in turn, be interconnected to the arm havingone end attached to the paddle vane. The thermal actuator units canoperate upon conductive heating along a conductive trace and theconductive heating can include the generation of a substantial portionof the heat in the area adjacent the first end. The conductive heatingtrace can include a thinned cross-section adjacent the first end. Theheating layers of the thermal actuator units can comprise substantiallyeither a copper nickel alloy or titanium nitride. The paddle can beconstructed from a similar conductive material to portions of thethermal actuator units however it is conductively insulated therefrom.

[0019] Preferably, the thermal actuator units are constructed frommultiple layers utilizing a single mask to etch the multiple layers.

[0020] The nozzle chamber can include an actuator access port in asecond surface of the chamber. The access port can comprise a slot in acorner of the chamber and the actuator is able to move in an arc throughthe slot. The actuator can include an end portion which matessubstantially with a wall of the chamber at substantially right anglesto the paddle vane. The paddle vane can include a depressed portionsubstantially opposite the fluid ejection port.

[0021] In accordance with a further aspect of the present invention,there is provided a thermal actuator including a series of lever armsattached at one end to a substrate, the thermal actuator beingoperational as a result of conductive heating of a conductive trace, theconductive trace including a thinned cross-section substantiallyadjacent the attachment to the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Notwithstanding any other forms which may fall within the scopeof the present invention, preferred forms of the invention will now bedescribed, by way of example only, with reference to the accompanyingdrawings in which:

[0023] FIGS. 1-3 illustrate the basic operational principles of thepreferred embodiment;

[0024]FIG. 4 illustrates a three dimensional view of a single ink jetnozzle arrangement constructed in accordance with the preferredembodiment;

[0025]FIG. 5 illustrates an array of the nozzle arrangements of FIG. 4;

[0026]FIG. 6 shows a table to be used with reference to FIGS. 7 to 16;and

[0027] FIGS. 7 to 16 show various stages in the manufacture of the inkjet nozzle arrangement of FIG. 4.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

[0028] In the preferred embodiment, there is provided a nozzlearrangement having a nozzle chamber containing ink and a thermalactuator connected to a paddle positioned within the chamber. Thethermal actuator device is actuated so as to eject ink from the nozzlechamber. The preferred embodiment includes a particular thermal actuatorwhich includes a series of tapered portions for providing conductiveheating of a conductive trace. The actuator is connected to the paddlevia an arm received through a slotted wall of the nozzle chamber. Theactuator arm has a mating shape so as to mate substantially with thesurfaces of the slot in the nozzle chamber wall.

[0029] Turning initially to FIGS. 1-3, there is provided schematicillustrations of the basic operation of a nozzle arrangement of theinvention. A nozzle chamber 1 is provided filled with ink 2 by means ofan ink inlet channel 3 which can be etched through a wafer substrate onwhich the nozzle chamber 1 rests. The nozzle chamber 1 further includesan ink ejection port 4 around which an ink meniscus forms.

[0030] Inside the nozzle chamber 1 is a paddle type device 7 which isinterconnected to an actuator 8 through a slot in the wall of the nozzlechamber 1. The actuator 8 includes a heater means eg. 9 located adjacentto an end portion of a post 10. The post 10 is fixed to a substrate.

[0031] When it is desired to eject a drop from the nozzle chamber 1, asillustrated in FIG. 2, the heater means 9 is heated so as to undergothermal expansion. Preferably, the heater means 9 itself or the otherportions of the actuator 8 are built from materials having a high bendefficiency where the bend efficiency is defined as${{bend}\quad {efficiency}} = \frac{{Young}^{\prime}s\quad {Modulus} \times ( {{Coefficient}\quad {of}\quad {thermal}\quad {Expansion}} )}{{Density} \times {Specific}\quad {Heat}\quad {Capacity}}$

[0032] A suitable material for the heater elements is a copper nickelalloy which can be formed so as to bend a glass material.

[0033] The heater means 9 is ideally located adjacent the end portion ofthe post 10 such that the effects of activation are magnified at thepaddle end 7 such that small thermal expansions near the post 10 resultin large movements of the paddle end.

[0034] The heater means 9 and consequential paddle movement causes ageneral increase in pressure around the ink meniscus 5 which expands, asillustrated in FIG. 2, in a rapid manner. The heater current is pulsedand ink is ejected out of the port 4 in addition to flowing in from theink channel 3.

[0035] Subsequently, the paddle 7 is deactivated to again return to itsquiescent position. The deactivation causes a general reflow of the inkinto the nozzle chamber. The forward momentum of the ink outside thenozzle rim and the corresponding backflow results in a general neckingand breaking off of the drop 12 which proceeds to the print media. Thecollapsed meniscus 5 results in a general sucking of ink into the nozzlechamber 2 via the ink flow channel 3. In time, the nozzle chamber 1 isrefilled such that the position in FIG. 1 is again reached and thenozzle chamber is subsequently ready for the ejection of another drop ofink.

[0036]FIG. 4 illustrates a side perspective view of the nozzlearrangement FIG. 5 illustrates sectional view through an array of nozzlearrangement of FIG. 4. In these figures, the numbering of elementspreviously introduced has been retained.

[0037] Firstly, the actuator 8 includes a series of tapered actuatorunits eg. 15 which comprise an upper glass portion (amorphous silicondioxide) 16 formed on top of a titanium nitride layer 17. Alternativelya copper nickel alloy layer (hereinafter called cupronickel) can beutilized which will have a higher bend efficiency where bend efficiencyis defined as:${{bend}\quad {efficiency}} = \frac{{Young}^{\prime}s\quad {Modulus} \times ( {{Coefficient}\quad {of}\quad {thermal}\quad {Expansion}} )}{{Density} \times {Specific}\quad {Heat}\quad {Capacity}}$

[0038] The titanium nitride layer 17 is in a tapered form and, as such,resistive heating takes place near an end portion of the post 10.Adjacent titanium nitride/glass portions 15 are interconnected at ablock portion 19 which also provides a mechanical structural support forthe actuator 8.

[0039] The heater means 9 ideally includes a plurality of the taperedactuator unit 15 which are elongate and spaced apart such that, uponheating, the bending force exhibited along the axis of the actuator 8 ismaximized. Slots are defined between adjacent tapered units 15 and allowfor slight differential operation of each actuator 8 with respect toadjacent actuators 8.

[0040] The block portion 19 is interconnected to an arm 20. The arm 20is in turn connected to the paddle 7 inside the nozzle chamber 1 bymeans of a slot eg. 22 formed in the side of the nozzle chamber 1. Theslot 22 is designed generally to mate with the surfaces of the arm 20 soas to minimise opportunities for the outflow of ink around the arm 20.The ink is held generally within the nozzle chamber 1 via surfacetension effects around the slot 22.

[0041] When it is desired to actuate the arm 20, a conductive current ispassed through the titanium nitride layer 17 via vias within the blockportion 19 connecting to a lower CMOS layer 6 which provides thenecessary power and control circuitry for the nozzle arrangement. Theconductive current results in heating of the nitride layer 17 adjacentto the post 10 which results in a general upward bending of the arm 20and consequential ejection of ink out of the nozzle 4. The ejected dropis printed on a page in the usual manner for an inkjet printer aspreviously described.

[0042] An array of nozzle arrangements can be formed so as to create asingle printhead. For example, in FIG. 5 there is illustrated a partlysectioned various array view which comprises multiple ink ejectionnozzle arrangements of FIG. 4 laid out in interleaved lines so as toform a printhead array. Of course, different types of arrays can beformulated including full color arrays etc.

[0043] The construction of the printhead system described can proceedutilizing standard MEMS techniques through suitable modification of thesteps as set out in the Australian Provisional Patent Specificationentitled “Image Creation Method and Apparatus (IJ 41)” filed by thepresent applicant simultaneously herewith the contents of which arefully incorporated by cross reference.

[0044] Fabrication of the ink jet nozzle arrangement is indicated inFIGS. 7 to 16. The preferred embodiment achieves a particular balancebetween utilization of the standard semi-conductor processing materialsuch as titanium nitride and glass in a MEMS process. Obviously theskilled person may make other choices of materials and design featureswhere the economics are justified. For example, a copper nickel alloy of50% copper and 50% nickel may be more advantageously deployed as theconductive heating compound as it is likely to have higher levels ofbend efficiency. Also, other design structures may be employed where itis not necessary to provide for such a simple form of manufacture.

[0045] The presently disclosed ink jet printing technology ispotentially suited to a wide range of printing system including: colourand monochrome office printers, short run digital printers, high speeddigital printers, offset press supplemental printers, low cost scanningprinters high speed pagewidth printers, notebook computers with inbuiltpagewidth printers, portable colour and monochrome printers, colour andmonochrome copiers, colour and monochrome facsimile machines, combinedprinter, facsimile and copying machines, label printers, large formatplotters, photograph copiers, printers for digital photographic“minilabs”, video printers, PHOTO CD (PHOTO CD is a registered trademark of the Eastman Kodak Company) printers, portable printers for PDAs,wallpaper printers, indoor sign printers, billboard printers, fabricprinters, camera printers and fault tolerant commercial printer arrays.

[0046] It would be appreciated by a person skilled in the art thatnumerous variations and/or modifications may be made to the presentinvention as shown in the specific embodiments without departing fromthe spirit or scope of the invention as broadly described. The presentembodiments are, therefore, to be considered in all respects to beillustrative and not restrictive.

Ink Jet Technologies

[0047] The embodiments of the invention use an ink jet printer typedevice. Of course many different devices could be used. Howeverpresently popular ink jet printing technologies are unlikely to besuitable.

[0048] The most significant problem with thermal ink jet is powerconsumption. This is approximately 100 times that required for highspeed, and stems from the energy-inefficient means of drop ejection.This involves the rapid boiling of water to produce a vapor bubble whichexpels the ink. Water has a very high heat capacity, and must besuperheated in thermal ink jet applications. This leads to an efficiencyof around 0.02%, from electricity input to drop momentum (and increasedsurface area) out.

[0049] The most significant problem with piezoelectric ink jet is sizeand cost. Piezoelectric crystals have a very small deflection atreasonable drive voltages, and therefore require a large area for eachnozzle. Also, each piezoelectric actuator must be connected to its drivecircuit on a separate substrate. This is not a significant problem atthe current limit of around 300 nozzles per printhead, but is a majorimpediment to the fabrication of pagewidth printheads with 19,200nozzles.

[0050] Ideally, the ink jet technologies used meet the stringentrequirements of in-camera digital color printing and other high quality,high speed, low cost printing applications. To meet the requirements ofdigital photography, new ink jet technologies have been created. Thetarget features include:

[0051] low power (less than 10 Watts)

[0052] high resolution capability (1,600 dpi or more)

[0053] photographic quality output

[0054] low manufacturing cost

[0055] small size (pagewidth times minimum cross section)

[0056] high speed (<2 seconds per page).

[0057] All of these features can be met or exceeded by the ink jetsystems described below with differing levels of difficulty. Forty-fivedifferent ink jet technologies have been developed by the Assignee togive a wide range of choices for high volume manufacture. Thesetechnologies form part of separate applications assigned to the presentAssignee as set out in the table under the heading Cross References toRelated Applications.

[0058] The ink jet designs shown here are suitable for a wide range ofdigital printing systems, from battery powered one-time use digitalcameras, through to desktop and network printers, and through tocommercial printing systems.

[0059] For ease of manufacture using standard process equipment, theprinthead is designed to be a monolithic 0.5 micron CMOS chip with MEMSpost processing. For color photographic applications, the printhead is100 mm long, with a width which depends upon the ink jet type. Thesmallest printhead designed is IJ38, which is 0.35 mm wide, giving achip area of 35 square mm. The printheads each contain 19,200 nozzlesplus data and control circuitry.

[0060] Ink is supplied to the back of the printhead by injection moldedplastic ink channels. The molding requires 50 micron features, which canbe created using a lithographically micromachined insert in a standardinjection molding tool. Ink flows through holes etched through the waferto the nozzle chambers fabricated on the front surface of the wafer. Theprinthead is connected to the camera circuitry by tape automatedbonding.

Tables of Drop-on-Demand Ink Jets

[0061] Eleven important characteristics of the fundamental operation ofindividual ink jet nozzles have been identified. These characteristicsare largely orthogonal, and so can be elucidated as an elevendimensional matrix. Most of the eleven axes of this matrix includeentries developed by the present assignee.

[0062] The following tables form the axes of an eleven dimensional tableof ink jet types.

[0063] Actuator mechanism (18 types)

[0064] Basic operation mode (7 types)

[0065] Auxiliary mechanism (8 types)

[0066] Actuator amplification or modification method (17 types)

[0067] Actuator motion (19 types)

[0068] Nozzle refill method (4 types)

[0069] Method of restricting back-flow through inlet (10 types)

[0070] Nozzle clearing method (9 types)

[0071] Nozzle plate construction (9 types)

[0072] Drop ejection direction (5 types)

[0073] Ink type (7 types)

[0074] The complete eleven dimensional table represented by these axescontains 36.9 billion possible configurations of ink jet nozzle. Whilenot all of the possible combinations result in a viable ink jettechnology, many million configurations are viable. It is clearlyimpractical to elucidate all of the possible configurations. Instead,certain ink jet types have been investigated in detail. These aredesignated IJ01 to IJ45 above which matches the docket numbers in thetable under the heading Cross References to Related Applications.

[0075] Other ink jet configurations can readily be derived from theseforty-five examples by substituting alternative configurations along oneor more of the 11 axes. Most of the IJ01 to IJ45 examples can be madeinto ink jet printheads with characteristics superior to any currentlyavailable ink jet technology.

[0076] Where there are prior art examples known to the inventor, one ormore of these examples are listed in the examples column of the tablesbelow. The IJ01 to IJ45 series are also listed in the examples column.In some cases, print technology may be listed more than once in a table,where it shares characteristics with more than one entry.

[0077] Suitable applications for the ink jet technologies include: Homeprinters, Office network printers, Short run digital printers,Commercial print systems, Fabric printers, Pocket printers, Internet WWWprinters, Video printers, Medical imaging, Wide format printers,Notebook PC printers, Fax machines, Industrial printing systems,Photocopiers, Photographic minilabs etc.

[0078] The information associated with the aforementioned 11 dimensionalmatrix are set out in the following tables. ACTUATOR MECHANISM (APPLIEDONLY TO SELECTED INK DROPS) Description Advantages DisadvantagesExamples Thermal An electrothermal Large force High power CanonBubblejet bubble heater heats the ink to generated Ink carrier 1979 Endoet al GB above boiling point, Simple limited to water patent 2,007,162transferring significant construction Low efficiency Xerox heater-in-heat to the aqueous No moving parts High pit 1990 Hawkins et ink. Abubble Fast operation temperatures al U.S. Pat. No. nucleates andquickly Small chip area required 4,899,181 forms, expelling the requiredfor actuator High mechanical Hewlett-Packard ink. stress TIJ 1982 Vaughtet The efficiency of the Unusual al U.S. Pat. No. process is low, withmaterials required 4,490,728 typically less than Large drive 0.05% ofthe electrical transistors energy being Cavitation causes transformedinto actuator failure kinetic energy of the Kogation reduces drop.bubble formation Large print heads are difficult to fabricate Piezo- Apiezoelectric crystal Low power Very large area Kyser et al electricsuch as lead consumption required for actuator U.S. Pat. No. 3,946,398lanthanum zirconate Many ink types Difficult to Zoltan U.S. Pat. (PZT)is electrically can be used integrate with No. 3,683,212 activated, andeither Fast operation electronics 1973 Stemme expands, shears, or Highefficiency High voltage U.S. Pat. No. 3,747,120 bends to apply drivetransistors Epson Stylus pressure to the ink, required Tektronixejecting drops. Full pagewidth IJ04 print heads impractical due toactuator size Requires electrical poling in high field strengths duringmanufacture Electro- An electric field is Low power Low maximum SeikoEpson, strictive used to activate consumption strain (approx. Usui etall JP electrostriction in Many ink types 0.01%) 253401/96 relaxormaterials such can be used Large area IJ04 as lead lanthanum Low thermalrequired for actuator zirconate titanate expansion due to low strain(PLZT) or lead Electric field Response speed magnesium niobate strengthrequired is marginal (˜10 (PMN). (approx. 3.5 V/μm) μs) can be generatedHigh voltage without difficulty drive transistors Does not requirerequired electrical poling Full pagewidth print heads impractical due toactuator size Ferro- An electric field is Low power Difficult to IJ04electric used to induce a phase consumption integrate with transitionbetween the Many ink types electronics antiferroelectric (AFE) can beused Unusual and ferroelectric (FE) Fast operation materials such asphase. Perovskite (<1 μs) PLZSnT are materials such as tin Relativelyhigh required modified lead longitudinal strain Actuators requirelanthanum zirconate High efficiency a large area titanate (PLZSnT)Electric field exhibit large strains of strength of around 3 up to 1%associated V/μm can be readily with the AFE to FE provided phasetransition. Electro- Conductive plates are Low power Difficult to IJ02,IJ04 static plates separated by a consumption operate electrostaticcompressible or fluid Many ink types devices in an dielectric (usuallyair). can be used aqueous Upon application of a Fast operationenvironment voltage, the plates The electrostatic attract each other andactuator will displace ink, causing normally need to be drop ejection.The separated from the conductive plates may ink be in a comb or Verylarge area honeycomb structure, required to achieve or stacked toincrease high forces the surface area and High voltage therefore theforce. drive transistors may be required Full pagewidth print heads arenot competitive due to actuator size Electro- A strong electric fieldLow current High voltage 1989 Saito et al, static pull is applied to theink, consumption required U.S. Pat. No. 4,799,068 on ink whereupon Lowtemperature May be damaged 1989 Miura et al, electrostatic attraction bysparks due to air U.S. Pat. No. 4,810,954 accelerates the ink breakdownTone-jet towards the print Required field medium. strength increases asthe drop size decreases High voltage drive transistors requiredElectrostatic field attracts dust Permanent An electromagnet Low powerComplex IJ07, IJ10 magnet directly attracts a consumption fabricationelectro- permanent magnet, Many ink types Permanent magnetic displacingink and can be used magnetic material causing drop ejection. Fastoperation such as Neodymium Rare earth magnets High efficiency IronBoron (NdFeB) with a field strength Easy extension required. around 1Tesla can be from single nozzles High local used. Examples are: topagewidth print currents required Samarium Cobalt heads Copper (SaCo)and magnetic metalization should materials in the be used for longneodymium iron boron electromigration family (NdFeB, lifetime and lowNdDyFeBNb, resistivity NdDyFeB, etc) Pigmented inks are usuallyinfeasible Operating temperature limited to the Curie temperature(around 540 K) Soft A solenoid induced a Low power Complex IJ01, IJ05,IJ08, magnetic magnetic field in a soft consumption fabrication IJ10,IJ12, IJ14, core electro- magnetic core or yoke Many ink types Materialsnot IJ15, IJ17 magnetic fabricated from a can be used usually present ina ferrous material such Fast operation CMOS fab such as as electroplatediron High efficiency NiFe, CoNiFe, or alloys such as CoNiFe Easyextension CoFe are required [1], CoFe, or NiFe from single nozzles Highlocal alloys. Typically, the to pagewidth print currents required softmagnetic material heads Copper is in two parts, which ♦ metalizationshould are normally held be used for long apart by a spring.electromigration When the solenoid is lifetime and low actuated, the twoparts resistivity attract, displacing the Electroplating is ink.required High saturation flux density is required (2.0-2.1 T isachievable with CoNiFe [1]) Lorenz The Lorenz force Low power Force actsas a IJ06, IJ11, IJ13, force acting on a current consumption twistingmotion IJ16 carrying wire in a Many ink types Typically, only a magneticfield is can be used quarter of the utilized. Fast operation solenoidlength This allows the High efficiency provides force in a magneticfield to be Easy extension useful direction supplied externally to fromsingle nozzles High local the print head, for to pagewidth printcurrents required example with rare heads Copper earth permanentmetalization should magnets. be used for long Only the currentelectromigration carrying wire need be lifetime and low fabricated onthe print- resistivity head, simplifying Pigmented inks materials areusually requirements. infeasible Magneto- The actuator uses the Many inktypes Force acts as a Fischenbeck, striction giant magnetostrictive canbe used twisting motion U.S. Pat. No. 4,032,929 effect of materials Fastoperation Unusual IJ25 such as Terfenol-D (an Easy extension materialssuch as alloy of terbium, from single nozzles Terfenol-D are dysprosiumand iron to pagewidth print required developed at the Naval heads Highlocal Ordnance Laboratory, High force is currents required henceTer-Fe-NOL). available Copper For best efficiency, the metalizationshould actuator should be pre- be used for long stressed to approx. 8electromigration MPa. lifetime and low resistivity Pre-stressing may berequired Surface Ink under positive Low power Requires Silverbrook, EPtension pressure is held in a consumption supplementary force 0771 658A2 and reduction nozzle by surface Simple to effect drop related patenttension. The surface construction separation applications tension of theink is No unusual Requires special reduced below the materials requiredin ink surfactants bubble threshold, fabrication Speed may be causingthe ink to High efficiency limited by surfactant egress from the Easyextension properties nozzle. from single nozzles to pagewidth printheads Viscosity The ink viscosity is Simple Requires Silverbrook, EPreduction locally reduced to construction supplementary force 0771 658A2 and select which drops are No unusual to effect drop related patentto be ejected. A materials required in separation applications viscosityreduction can fabrication Requires special be achieved Easy extensionink viscosity electrothermally with from single nozzles properties mostinks, but special to pagewidth print High speed is inks can beengineered heads difficult to achieve for a 100:1 viscosity Requiresreduction. oscillating ink pressure A high temperature difference(typically 80 degrees) is required Acoustic An acoustic wave is Canoperate Complex drive 1993 Hadimioglu generated and without a nozzlecircuitry et al, EUP 550,192 focussed upon the plate Complex 1993 Elrodet al, drop ejection region. fabrication EUP 572,220 Low efficiency Poorcontrol of drop position Poor control of drop volume Thermo- An actuatorwhich Low power Efficient aqueous IJ03, IJ09, IJ17, elastic bend reliesupon differential consumption operation requires a IJ18, IJ19, IJ20,actuator thermal expansion Many ink types thermal insulator on IJ21,IJ22, IJ23, upon Joule heating is can be used the hot side IJ24, IJ27,IJ28, used. Simple planar Corrosion IJ29, IJ30, IJ31, fabricationprevention can be IJ32, IJ33, IJ34, Small chip area difficult IJ35,IJ36, IJ37, required for each Pigmented inks IJ38 ,IJ39, IJ40, actuatormay be infeasible, IJ41 Fast operation as pigment particles Highefficiency may jam the bend CMOS actuator compatible voltages andcurrents Standard MEMS processes can be used Easy extension from singlenozzles to pagewidth print heads High CTE A material with a very Highforce can Requires special IJ09, IJ17, IJ18, thermo- high coefficient ofbe generated material (e.g. PTFE) IJ20, IJ21, IJ22, elastic thermalexpansion Three methods of Requires a PTFE IJ23, IJ24, IJ27, actuator(CTE) such as PTFE deposition are deposition process, IJ28, IJ29, IJ30,polytetrafluoroethylene under development: which is not yet IJ31, IJ42,IJ43, (PTFE) is used. As chemical vapor standard in ULSI IJ44 high CTEmaterials deposition (CVD), fabs are usually non- spin coating, and PTFEdeposition conductive, a heater evaporation cannot be followedfabricated from a PTFE is a with high conductive material is candidatefor low temperature (above incorporated. A 50 μm dielectric constant350° C.) processing long PTFE bend insulation in ULSI Pigmented inksactuator with Very low power may be infeasible, polysilicon heater andconsumption as pigment particles 15 mW power input Many ink types mayjam the bend can provide 180 μN can be used actuator force and 10 μmSimple planar deflection. Actuator fabrication motions include: Smallchip area Bend required for each Push actuator Buckle Fast operationRotate High efficiency CMOS compatible voltages and currents Easyextension from single nozzles to pagewidth print heads Conduct-ive Apolymer with a high High force can Requires special IJ24 polymercoefficient of thermal be generated materials thermo- expansion (such asVery low power development (High elastic PTFE) is doped with consumptionCTE conductive actuator conducting substances Many ink types polymer) toincrease its can be used Requires a PTFE conductivity to about 3 Simpleplanar deposition process, orders of magnitude fabrication which is notyet below that of copper. Small chip area standard in ULSI Theconducting required for each fabs polymer expands actuator PTFEdeposition when resistively Fast operation cannot be followed heated.High efficiency with high Examples of CMOS temperature (above conductingdopants compatible voltages 350° C.) processing include: and currentsEvaporation and Carbon nanotubes Easy extension CVD deposition Metalfibers from single nozzles techniques cannot Conductive polymers topagewidth print be used such as doped heads Pigmented inks polythiophenemay be infeasible, Carbon granules as pigment particles may jam the bendactuator Shape A shape memory alloy High force is Fatigue limits IJ26memory such as TiNi (also available (stresses maximum number alloy knownas Nitinol - of hundreds of MPa) of cycles Nickel Titanium alloy Largestrain is Low strain (1%) developed at the Naval available (more than isrequired to extend Ordnance Laboratory) 3%) fatigue resistance isthermally switched High corrosion Cycle rate between its weak resistancelimited by heat martensitic state and Simple removal its high stiffnessconstruction Requires unusual austenic state. The Easy extensionmaterials (TiNi) shape of the actuator from single nozzles The latentheat of in its martensitic state to pagewidth print transformation mustis deformed relative to heads be provided the austenic shape. Lowvoltage High current The shape change operation operation causesejection of a Requires pre- drop. stressing to distort the martensiticstate Linear Linear magnetic Linear Magnetic Requires unusual IJ12Magnetic actuators include the actuators can be semiconductor ActuatorLinear Induction constructed with materials such as Actuator (LIA),Linear high thrust, long soft magnetic alloys Permanent Magnet travel,and high (e.g. CoNiFe) Synchronous Actuator efficiency using Somevarieties (LPMSA), Linear planar also require Reluctance semiconductorpermanent magnetic Synchronous Actuator fabrication materials such as(LRSA), Linear techniques Neodymium iron Switched Reluctance Longactuator boron (NdFeB) Actuator (LSRA), and travel is available Requiresthe Linear Stepper Medium force is complex multi- Actuator (LSA).available phase drive circuitry Low voltage High current operationoperation

[0079] BASIC OPERATION MODE Description Advantages DisadvantagesExamples Actuator This is the simplest Simple operation Drop repetitionThermal ink jet directly mode of operation: the No external rate isusually Piezoelectric ink pushes ink actuator directly fields requiredlimited to around 10 jet supplies sufficient Satellite drops kHz.However, this IJ01, IJ02, IJ03, kinetic energy to expel can be avoidedif is not fundamental IJ04, IJ05, IJ06, the drop. The drop drop velocityis less to the method, but is IJ07, IJ09, IJ11, must have a sufficientthan 4 m/s related to the refill IJ12, IJ14, IJ16, velocity to overcomeCan be efficient, method normally IJ20, IJ22, IJ23, the surface tension.depending upon the used IJ24, IJ25, IJ26, actuator used All of the dropIJ27, IJ28, IJ29, kinetic energy must IJ30, IJ31, IJ32, be provided bythe IJ33, IJ34, IJ35, actuator IJ36, IJ37, IJ38, Satellite drops IJ39,IJ40, IJ41, usually form if drop IJ42, IJ43, IJ44 velocity is greaterthan 4.5 m/s Proximity The drops to be Very simple print Requires closeSilverbrook, EP printed are selected by head fabrication can proximitybetween 0771 658 A2 and some manner (e.g. be used the print head andrelated patent thermally induced The drop the print media orapplications surface tension selection means transfer roller reductionof does not need to May require two pressurized ink). provide the energyprint heads printing Selected drops are required to separate alternaterows of the separated from the ink the drop from the image in the nozzleby nozzle Monolithic color contact with the print print heads are mediumor a transfer difficult roller. Electro- The drops to be Very simpleprint Requires very Silverbrook, EP static pull printed are selected byhead fabrication can high electrostatic 0771 658 A2 and on ink somemanner (e.g. be used field related patent thermally induced The dropElectrostatic field applications surface tension selection means forsmall nozzle Tone-Jet reduction of does not need to sizes is above airpressurized ink). provide the energy breakdown Selected drops arerequired to separate Electrostatic field separated from the ink the dropfrom the may attract dust in the nozzle by a nozzle strong electricfield. Magnetic The drops to be Very simple print Requires Silverbrook,EP pull on ink printed are selected by head fabrication can magnetic ink0771 658 A2 and some manner (e.g. be used Ink colors other relatedpatent thermally induced The drop than black are applications surfacetension selection means difficult reduction of does not need to Requiresvery pressurized ink). provide the energy high magnetic fields Selecteddrops are required to separate separated from the ink the drop from thein the nozzle by a nozzle strong magnetic field acting on the magneticink. Shutter The actuator moves a High speed (>50 Moving parts are IJ13,IJ17, IJ21 shutter to block ink kHz) operation can required flow to thenozzle. The be achieved due to Requires ink ink pressure is pulsedreduced refill time pressure modulator at a multiple of the Drop timingcan Friction and wear drop ejection be very accurate must be consideredfrequency. The actuator Stiction is energy can be very possible lowShuttered The actuator moves a Actuators with Moving parts are IJ08,IJ15, IJ18, grill shutter to block ink small travel can be required IJ19flow through a grill to used Requires ink the nozzle. The shutterActuators with pressure modulator movement need only small force can beFriction and wear be equal to the width used must be considered ofthegrill holes. High speed (>50 Stiction is kHz) operation can possiblebe achieved Pulsed A pulsed magnetic Extremely low Requires an IJ10magnetic field attracts an ‘ink energy operation is external pulsed pullon ink pusher’ at the drop possible magnetic field pusher ejectionfrequency. An No heat Requires special actuator controls a dissipationmaterials for both catch, which prevents problems the actuator and thethe ink pusher from ink pusher moving when a drop is Complex not to beejected. construction

[0080] AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) DescriptionAdvantages Disadvantages Examples None The actuator directly Simplicityof Drop ejection Most ink jets, fires the ink drop, and constructionenergy must be including there is no external Simplicity of supplied bypiezoelectric and field or other operation individual nozzle thermalbubble. mechanism required. Small physical actuator IJ01, IJ02, IJ03,size IJ04, IJ05, IJ07, IJ09, IJ11, IJ12, IJ14, IJ20, IJ22, IJ23, IJ24,IJ25, IJ26, IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ35, IJ36,IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Oscillating The inkpressure Oscillating ink Requires external Silverbrook, EP ink pressureoscillates, providing pressure can provide ink pressure 0771 658 A2 and(including much of the drop a refill pulse, oscillator related patentacoustic ejection energy. The allowing higher Ink pressure applicationsstimul- actuator selects which operating speed phase and amplitude IJ08,IJ13, IJ15, ation) drops are to be fired The actuators must be carefullyIJ17, IJ18, IJ19, by selectively may operate with controlled IJ21blocking or enabling much lower energy Acoustic nozzles. The inkAcoustic lenses reflections in the ink pressure oscillation can be usedto focus chamber must be may be achieved by the sound on the designedfor vibrating the print nozzles head, or preferably by an actuator inthe ink supply. Media The print head is Low power Precision Silverbrook,EP proximity placed in close High accuracy assembly required 0771 658 A2and proximity to the print Simple print head Paper fibers may relatedpatent medium. Selected construction cause problems applications dropsprotrude from Cannot print on the print head further rough substratesthan unselected drops, and contact the print medium. The drop soaks intothe medium fast enough to cause drop separation. Transfer Drops areprinted to a High accuracy Bulky Silverbrook, EP roller transfer rollerinstead Wide range of Expensive 0771 658 A2 and of straight to the printprint substrates can Complex related patent medium. A transfer be usedconstruction applications roller can also be used Ink can be driedTektronix hot for proximity drop on the transfer roller meltpiezoelectric separation. ink jet Any of the IJ series Electro- Anelectric field is Low power Field strength Silverbrook, EP static usedto accelerate Simple print head required for 0771 658 A2 and selecteddrops towards construction separation of small related patent the printmedium. drops is near or applications above air Tone-Jet breakdownDirect A magnetic field is Low power Requires Silverbrook, EP magneticused to accelerate Simple print head magnetic ink 0771 658 A2 and fieldselected drops of construction Requires strong related patent magneticink towards magnetic field applications the print medium. Cross Theprint head is Does not require Requires external IJ06, IJ16 magneticplaced in a constant magnetic materials magnet field magnetic field. Theto be integrated in Current densities Lorenz force in a the print headmay be high, current carrying wire manufacturing resulting in is used tomove the process electromigration actuator. problems Pulsed A pulsedmagnetic Very low power Complex print IJ10 magnetic field is used tooperation is possible head construction field cyclically attract a Smallprint head Magnetic paddle, which pushes size materials required in onthe ink. A small print head actuator moves a catch, which selectivelyprevents the paddle from moving.

[0081] ACTUATOR AMPLIFICATION OR MODIFICATION METHOD DescriptionAdvantages Disadvantages Examples None No actuator Operational Manyactuator Thermal Bubble mechanical simplicity mechanisms have InkJetamplification is used. insufficient travel, IJ01, IJ02, IJ06, Theactuator directly or insufficient force, IJ07, IJ16, IJ25, drives thedrop to efficiently drive IJ26 ejection process. the drop ejectionprocess Differential An actuator material Provides greater High stressesare Piezoelectric expansion expands more on one travel in a reducedinvolved IJ03, IJ09, IJ17, bend side than on the other. print head areaCare must be IJ18, IJ19, IJ20, actuator The expansion may be taken thatthe IJ21, IJ22, IJ23, thermal, piezoelectric, materials do not IJ24,IJ27, IJ29, magnetostrictive, or delaminate IJ30, IJ31, IJ32, othermechanism. The Residual bend IJ33, IJ34, IJ35, bend actuator convertsresulting from high IJ36, IJ37, IJ38, a high force low traveltemperature or high IJ39, IJ42, IJ43, actuator mechanism to stressduring IJ44 high travel, lower formation force mechanism. Transient Atrilayer bend Very good High stresses are IJ40, IJ41 bend actuator wherethe two temperature stability involved actuator outside layers are Highspeed, as a Care must be identical. This cancels new drop can be takenthat the bend due to ambient fired before heat materials do nottemperature and dissipates delaminate residual stress. The Cancelsresidual actuator only responds stress of formation to transient heatingof one side or the other. Reverse The actuator loads a Better couplingFabrication IJ05, IJ11 spring spring. When the to the ink complexityactuator is turned off, High stress in the the spring releases. springThis can reverse the force/distance curve of the actuator to make itcompatible with the force/time requirements of the drop ejection.Actuator A series of thin Increased travel Increased Some stackactuators are stacked. Reduced drive fabrication piezoelectric ink jetsThis can be voltage complexity IJ04 appropriate where Increasedactuators require high possibility of short electric field strength,circuits due to such as electrostatic pinholes and piezoelectricactuators. Multiple Multiple smaller Increases the Actuator forces IJ12,IJ13, IJ18, actuators actuators are used force available from may notadd IJ20, IJ22, IJ28, simultaneously to an actuator linearly, reducingIJ42, IJ43 move the ink. Each Multiple efficiency actuator need provideactuators can be only a portion of the positioned to control forcerequired. ink flow accurately Linear A linear spring is used Matches lowRequires print IJ15 Spring to transform a motion travel actuator withhead area for the with small travel and higher travel spring high forceinto a requirements longer travel, lower Non-contact force motion.method of motion transformation Coiled A bend actuator is Increasestravel Generally IJ17, IJ21, IJ34, actuator coiled to provide Reduceschip restricted to planar IJ35 greater travel in a area implementationsreduced chip area. Planar due to extreme implementations are fabricationdifficulty relatively easy to in other orientations. fabricate. FlexureA bend actuator has a Simple means of Care must be IJ10, IJ19, IJ33 bendsmall region near the increasing travel of taken not to exceed actuatorfixture point, which a bend actuator the elastic limit in flexes muchmore the flexure area readily than the Stress remainder of thedistribution is very actuator. The actuator uneven flexing iseffectively Difficult to converted from an accurately model even coilingto an with finite element angular bend, resulting analysis in greatertravel of the actuator tip. Catch The actuator controls a Very lowComplex IJ10 small catch. The catch actuator energy construction eitherenables or Very small Requires external disables movement of actuatorsize force an ink pusher that is Unsuitable for controlled in a bulkpigmented inks manner. Gears Gears can be used to Low force, low Movingparts are IJ13 increase travel at the travel actuators can requiredexpense of duration. be used Several actuator Circular gears, rack Canbe fabricated cycles are required and pinion, ratchets, using standardMore complex and other gearing surface MEMS drive electronics methodscan be used. processes Complex construction Friction, friction, and wearare possible Buckle plate A buckle plate can be Very fast Must staywithin S. Hirata et al, used to change a slow movement elastic limits ofthe “An Ink-jet Head actuator into a fast achievable materials for longUsing Diaphragm motion. It can also device life Microactuator”, converta high force, High stresses Proc. IEEE MEMS, low travel actuatorinvolved Feb. 1996, pp 418- into a high travel, Generally high 423.medium force motion. power requirement IJ18, IJ27 Tapered A taperedmagnetic Linearizes the Complex IJ14 magnetic pole can increase magneticconstruction pole travel at the expense force/distance curve of force.Lever A lever and fulcrum is Matches low High stress IJ32, IJ36, IJ37used to transform a travel actuator with around the fulcrum motion withsmall higher travel travel and high force requirements into a motionwith Fulcrum area has longer travel and no linear movement, lower force.The lever and can be used for can also reverse the a fluid sealdirection of travel. Rotary The actuator is High mechanical Complex IJ28impeller connected to a rotary advantage construction impeller. A smallThe ratio of force Unsuitable for angular deflection of to travel of thepigmented inks the actuator results in actuator can be a rotation of thematched to the impeller vanes, which nozzle requirements push the inkagainst by varying the stationary vanes and number of impeller out ofthe nozzle. vanes Acoustic A refractive or No moving parts Large area1993 Hadimioglu lens diffractive (e.g. zone required et al, EUP 550,192plate) acoustic lens is Only relevant for 1993 Elrod et al, used toconcentrate acoustic ink jets EUP 572,220 sound waves. Sharp A sharppoint is used Simple Difficult to Tone-jet conductive to concentrate anconstruction fabricate using point electrostatic field. standard VLSIprocesses for a surface ejecting ink- jet Only relevant forelectrostatic ink jets

[0082] ACTUATOR MOTION Description Advantages Disadvantages ExamplesVolume The volume of the Simple High energy is Hewlett-Packard expansionactuator changes, construction in the typically required to Thermal Inkjet pushing the ink in all case of thermal ink achieve volume CanonBubblejet directions. jet expansion. This leads to thermal stress,cavitation, and kogation in thermal ink jet implementations Linear, Theactuator moves in Efficient High fabrication IJ01, IJ02, IJ04, normal toa direction normal to coupling to ink complexity may be IJ07, IJ11, IJ14chip surface the print head surface. drops ejected required to achieveThe nozzle is typically normal to the perpendicular in the line ofsurface motion movement. Parallel to The actuator moves Suitable forFabrication IJ12, IJ13, IJ15, chip surface parallel to the print planarfabrication complexity IJ33,, IJ34, IJ35, head surface. Drop FrictionIJ36 ejection may still be Stiction normal to the surface. Membrane Anactuator with a The effective Fabrication 1982 Howkins push high forcebut small area of the actuator complexity U.S. Pat. No. 4,459,601 areais used to push a becomes the Actuator size stiff membrane that ismembrane area Difficulty of in contact with the ink. integration in aVLSI process Rotary The actuator causes Rotary levers Device IJ05, IJ08,IJ13, the rotation of some may be used to complexity IJ28 element, sucha grill or increase travel May have impeller Small chip area friction ata pivot requirements point Bend The actuator bends A very small Requiresthe 1970 Kyser et al when energized. This change in actuator to be madeU.S. Pat. No. 3,946,398 may be due to dimensions can be from at leasttwo 1973 Stemme differential thermal converted to a large distinctlayers, or to U.S. Pat. No. 3,747,120 expansion, motion. have a thermalIJ03, IJ09, IJ10, piezoelectric difference across the IJ19, IJ23, IJ24,expansion, actuator IJ25, IJ29, IJ30, magnetostriction, or IJ31, IJ33,IJ34, other form of relative IJ35 dimensional change. Swivel Theactuator swivels Allows operation Inefficient IJ06 around a centralpivot. where the net linear coupling to the ink This motion is suitableforce on the paddle motion where there are is zero opposite forces Smallchip area applied to opposite requirements sides of the paddle, e.g.Lorenz force. Straighten The actuator is Can be used with Requirescareful IJ26, IJ32 normally bent, and shape memory balance of stressesstraightens when alloys where the to ensure that the energized. austenicphase is quiescent bend is planar accurate Double The actuator bends inOne actuator can Difficult to make IJ36, IJ37, IJ38 bend one directionwhen be used to power the drops ejected by one element is two nozzles.both bend directions energized, and bends Reduced chip identical. theother way when size. A small another element is Not sensitive toefficiency loss energized. ambient temperature compared to equivalentsingle bend actuators. Shear Energizing the Can increase the Not readily1985 Fishbeck actuator causes a shear effective travel of applicable toother U.S. Pat. No. 4,584,590 motion in the actuator piezoelectricactuator material. actuators mechanisms Radial con- The actuatorsqueezes Relatively easy High force 1970 Zoltan striction an inkreservoir, to fabricate single required U.S. Pat. No. 3,683,212 forcingink from a nozzles from glass Inefficient constricted nozzle. tubing asDifficult to macroscopic integrate with VLSI structures processesCoil/uncoil A coiled actuator Easy to fabricate Difficult to IJ17, IJ21,IJ34, uncoils or coils more as a planar VLSI fabricate for non- IJ35tightly. The motion of process planar devices the free end of the Smallarea Poor out-of-plane actuator ejects the ink. required, thereforestiffness low cost Bow The actuator bows (or Can increase the Maximumtravel IJ16, IJ18, IJ27 buckles) in the middle speed of travel isconstrained when energized. Mechanically High force rigid requiredPush-Pull Two actuators control The structure is Not readily IJ18 ashutter. One actuator pinned at both ends, suitable for ink jets pullsthe shutter, and so has a high out-of- which directly push the otherpushes it. plane rigidity the ink Curl A set of actuators curl Goodfluid flow Design IJ20, IJ42 inwards inwards to reduce the to the regionbehind complexity volume of ink that the actuator they enclose.increases efficiency Curl A set of actuators curl Relatively simpleRelatively large IJ43 outwards outwards, pressurizing construction chiparea ink in a chamber surrounding the actuators, and expelling ink froma nozzle in the chamber. Iris Multiple vanes enclose High efficiencyHigh fabrication IJ22 a volume of ink. These Small chip area complexitysimultaneously rotate, Not suitable for reducing the volume pigmentedinks between the vanes. Acoustic The actuator vibrates The actuator canLarge area 1993 Hadimioglu vibration at a high frequency. be physicallydistant required for et al, EUP 550,192 from the ink efficient operation1993 Elrod et al, at useful frequencies EUP 572,220 Acoustic couplingand crosstalk Complex drive circuitry Poor control of drop volume andposition None In various ink jet No moving parts Various otherSilverbrook, EP designs the actuator tradeoffs are 0771 658 A2 and doesnot move. required to related patent eliminate moving applications partsTone-jet

[0083] NOZZLE REFILL METHOD Description Advantages DisadvantagesExamples Surface This is the normal way Fabrication Low speed Thermalink jet tension that ink jets are simplicity Surface tensionPiezoelectric ink refilled. After the Operational force relatively jetactuator is energized, simplicity small compared to IJ01-IJ07, IJ10- ittypically returns actuator force IJ14, IJ16, IJ20, rapidly to its normalLong refill time IJ22-IJ45 position. This rapid usually dominates returnsucks in air the total repetition through the nozzle rate opening. Theink surface tension at the nozzle then exerts a small force restoringthe meniscus to a minimum area. This force refills the nozzle. ShutteredInk to the nozzle High speed Requires IJ08, IJ13, IJ15, oscillatingchamber is provided at Low actuator common ink IJ17, IJ18, IJ19, inkpressure a pressure that energy, as the pressure oscillator IJ21oscillates at twice the actuator need only May not be drop ejection openor close the suitable for frequency. When a shutter, instead ofpigmented inks drop is to be ejected, ejecting the ink drop the shutteris opened for 3 half cycles: drop ejection, actuator return, and refill.The shutter is then closed to prevent the nozzle chamber emptying duringthe next negative pressure cycle. Refill After the main High speed, asRequires two IJ09 actuator actuator has ejected a the nozzle isindependent drop a second (refill) actively refilled actuators pernozzle actuator is energized. The refill actuator pushes ink into thenozzle chamber. The refill actuator returns slowly, to prevent itsreturn from emptying the chamber again. Positive ink The ink is held aslight High refill rate, Surface spill Silverbrook, EP pressure positivepressure. therefore a high must be prevented 0771 658 A2 and After theink drop is drop repetition rate Highly related patent ejected, thenozzle is possible hydrophobic print applications chamber fills quicklyhead surfaces are Alternative for:, as surface tension and requiredIJ01-IJ07, IJ10-IJ14, ink pressure both IJ16, IJ20, IJ22-IJ45 operate torefill the nozzle.

[0084] METHOD OF RESTRICTING BACK-FLOW THROUGH INLET DescriptionAdvantages Disadvantages Examples Long inlet The ink inlet channelDesign simplicity Restricts refill Thermal ink jet channel to the nozzlechamber Operational rate Piezoelectric ink is made long and simplicityMay result in a jet relatively narrow, Reduces relatively large chipIJ42, IJ43 relying on viscous crosstalk area drag to reduce inlet Onlypartially back-flow. effective Positive ink The ink is under a Dropselection Requires a Silverbrook, EP pressure positive pressure, so andseparation method (such as a 0771 658 A2 and that in the quiescentforces can be nozzle rim or related patent state some of the ink reducedeffective applications drop already protrudes Fast refill timehydrophobizing, or Possible from the nozzle. both) to prevent operationof the This reduces the flooding of the following: IJ01- pressure in thenozzle ejection surface of IJ07, IJ09-IJ12, chamber which is the printhead. IJ14, IJ16, IJ20, required to eject a IJ22,, IJ23-IJ34, certainvolume of ink. IJ36-IJ41, IJ44 The reduction in chamber pressure resultsin a reduction in ink pushed out through the inlet. Baffle One or morebaffles The refill rate is Design HP Thermal Ink are placed in the inletnot as restricted as complexity Jet ink flow. When the the long inletMay increase Tektronix actuator is energized, method. fabricationpiezoelectric ink jet the rapid ink Reduces complexity (e.g. movementcreates crosstalk Tektronix hot melt eddies which restrict Piezoelectricprint the flow through the heads). inlet. The slower refill process isunrestricted, and does not result in eddies. Flexible flap In thismethod recently Significantly Not applicable to Canon restrictsdisclosed by Canon, reduces back-flow most ink jet inlet the expandingactuator for edge-shooter configurations (bubble) pushes on a thermalink jet Increased flexible flap that devices fabrication restricts theinlet. complexity Inelastic deformation of polymer flap results in creepover extended use Inlet Filter A filter is located Additional Restrictsrefill IJ04, IJ12, IJ24, between the ink inlet advantage of ink rateIJ27, IJ29, IJ30 and the nozzle filtration May result in chamber. Thefilter Ink filter may be complex has a multitude of fabricated with noconstruction small holes or slots, additional process restricting inkflow. steps The filter also removes particles which may block thenozzle. Small inlet The ink inlet channel Design simplicity Restrictsrefill IJ02, IJ37, IJ44 compared to the nozzle chamber rate to nozzlehas a substantially May result in a smaller cross section relativelylarge chip than that of the nozzle, area resulting in easier ink Onlypartially egress out of the effective nozzle than out of the inlet.Inlet shutter A secondary actuator Increases speed Requires separateIJ09 controls the position of of the ink-jet print refill actuator and ashutter, closing off head operation drive circuit the ink inlet when themain actuator is energized. The inlet is The method avoids the Back-flowRequires careful IJ01, IJ03, 1J05, located problem of inlet back-problem is design to minimize IJ06, IJ07, IJ10, behind the flow byarranging the eliminated the negative IJ11, IJ14, IJ16, ink-pushingink-pushing surface of pressure behind the IJ22, IJ23, IJ25, surface theactuator between paddle IJ28, IJ31, IJ32, the inlet and the IJ33, IJ34,IJ35, nozzle. IJ36, IJ39, IJ40, IJ41 Part of the The actuator and aSignificant Small increase in IJ07, IJ20, IJ26, actuator wall of the inkreductions in back- fabrication IJ38 moves to chamber are arranged flowcan be complexity shut off the so that the motion of achieved inlet theactuator closes off Compact designs the inlet. possible Nozzle In someconfigurations Ink back-flow None related to Silverbrook, EP actuator ofink jet, there is no problem is ink back-flow on 0771 658 A2 and doesnot expansion or eliminated actuation related patent result in inkmovement of an applications back-flow actuator which may Valve-jet causeink back-flow Tone-jet through the inlet.

[0085] NOZZLE CLEARING METHOD Description Advantages DisadvantagesExamples Normal All of the nozzles are No added May not be Most ink jetnozzle firing fired periodically, complexity on the sufficient tosystems before the ink has a print head displace dried ink IJ01, IJ02,IJ03, chance to dry. When IJ04, IJ05, IJ06, not in use the nozzles IJ07,IJ09, IJ10, are sealed (capped) IJ11, IJ12, IJ14, against air. IJ16,IJ20, IJ22, The nozzle firing is IJ23, IJ24, IJ25, usually performedIJ26, IJ27, IJ28, during a special IJ29, 1J30, IJ31, clearing cycle,after IJ32, IJ33, IJ34, first moving the print IJ36, IJ37, IJ38, head toa cleaning IJ39, IJ40,, IJ41, station. IJ42, IJ43, IJ44,, IJ45 Extra Insystems which heat Can be highly Requires higher Silverbrook, EP powerto the ink, but do not boil effective if the drive voltage for 0771 658A2 and ink heater it under normal heater is adjacent to clearing relatedpatent situations, nozzle the nozzle May require applications clearingcan be larger drive achieved by over- transistors powering the heaterand boiling ink at the nozzle. Rapid The actuator is fired in Does notrequire Effectiveness May be used success-ion rapid succession. In extradrive circuits depends with: IJ01, IJ02, of actuator someconfigurations, on the print head substantially upon IJ03, IJ04, IJ05,pulses this may cause heat Can be readily the configuration of IJ06,IJ07, IJ09, build-up at the nozzle controlled and the ink jet nozzleIJ10, IJ11, IJ14, which boils the ink, initiated by digital IJ16, IJ20,IJ22, clearing the nozzle. In logic IJ23, IJ24, IJ25, other situations,it may IJ27, IJ28, IJ29, cause sufficient IJ30, IJ31, IJ32, vibrationsto dislodge IJ33, IJ34, IJ36, clogged nozzles. IJ37, IJ38, IJ39, IJ40,IJ41, IJ42, IJ43, IJ44, IJ45 Extra Where an actuator is A simple Notsuitable May be used power to not normally driven to solution wherewhere there is a with: IJ03, IJ09, ink pushing the limit of its motion,applicable hard limit to IJ16, IJ20, IJ23, actuator nozzle clearing maybe actuator movement IJ24, IJ25, IJ27, assisted by providing IJ29, IJ30,IJ31, an enhanced drive IJ32, IJ39, IJ40, signal to the actuator. IJ41,IJ42, IJ43, IJ44, IJ45 Acoustic An ultrasonic wave is A high nozzle HighIJ08, IJ13, IJ15, resonance applied to the ink clearing capabilityimplementation cost IJ17, IJ18, IJ19, chamber. This wave is can beachieved if system does not IJ21 of an appropriate May be alreadyinclude an amplitude and implemented at very acoustic actuator frequencyto cause low cost in systems sufficient force at the which alreadynozzle to clear include acoustic blockages. This is actuators easiest toachieve if the ultrasonic wave is at a resonant frequency of the inkcavity. Nozzle A microfabricated Can clear Accurate Silverbrook, EPclearing plate is pushed against severely clogged mechanical 0771 658 A2and plate the nozzles. The plate nozzles alignment is related patent hasa post for every required applications nozzle. A post moves Moving partsare through each nozzle, required displacing dried ink. There is risk ofdamage to the nozzles Accurate fabrication is required Ink The pressureof the ink May be effective Requires May be used pressure is temporarilywhere other pressure pump or with all IJ series ink pulse increased sothat ink methods cannot be other pressure jets streams from all of theused actuator nozzles. This may be Expensive used in conjunctionWasteful of ink with actuator energizing. Print head A flexible ‘blade’is Effective for Difficult to use if Many ink jet wiper wiped across theprint planar print head print head surface is systems head surface. Thesurfaces non-planar or very blade is usually Low cost fragile fabricatedfrom a Requires flexible polymer, e.g. mechanical parts rubber orsynthetic Blade can wear elastomer. out in high volume print systemsSeparate A separate heater is Can be effective Fabrication Can be usedwith ink boiling provided at the nozzle where other nozzle complexitymany IJ series ink heater although the normal clearing methods jets drope-ection cannot be used mechanism does not Can be require it. Theheaters implemented at no do not require additional cost in individualdrive some ink jet circuits, as many configurations nozzles can becleared simultaneously, and no imaging is required.

[0086] NOZZLE PLATE CONSTRUCTION Description Advantages DisadvantagesExamples Electro- A nozzle plate is Fabrication High Hewlett Packardformed separately fabricated simplicity temperatures and Thermal Ink jetnickel from electroformed pressures are nickel, and bonded to requiredto bond the print head chip. nozzle plate Minimum thickness constraintsDifferential thermal expansion Laser Individual nozzle No masks Eachhole must Canon Bubblejet ablated or holes are ablated by an required beindividually 1988 Sercel et drilled intense UV laser in a Can be quitefast formed al., SPIE, Vol. 998 polymer nozzle plate, which is Somecontrol Special Excimer Beam typically a polymer over nozzle profileequipment required Applications, pp. such as polyimide or is possibleSlow where there 76-83 polysulphone Equipment are many thousands 1993Watanabe required is relatively of nozzles per print et al., U.S. Pat.No. low cost head 5,208,604 May produce thin burrs at exit holes SiliconA separate nozzle High accuracy is Two part K. Bean, IEEE micro- plateis attainable construction Transactions on machined micromachined fromHigh cost Electron Devices, single crystal silicon, Requires Vol. ED-25,No. 10, and bonded to the precision alignment 1978, pp 1185-1195 printhead wafer. Nozzles may be Xerox 1990 clogged by adhesive Hawkins etal., U.S. Pat. No. 4,899,181 Glass Fineglass capillaries No expensiveVery small 1970 Zoltan capillaries are drawn from glass equipmentrequired nozzle sizes are U.S. Pat. No. 3,683,212 tubing. This methodSimple to make difficult to form has been used for single nozzles Notsuited for making individual mass production nozzles, but is difficultto use for bulk manufacturing of print heads with thousands of nozzles.Monolithic, The nozzle plate is High accuracy Requires Silverbrook, EPsurface deposited as a layer (<1 μm) sacrificial layer 0771 658 A2 andmicro- using standard VLSI Monolithic under the nozzle related patentmachined deposition techniques. Low cost plate to form the applicationsusing VLSI Nozzles are etched in Existing nozzle chamber IJ01, IJ02,IJ04, litho- the nozzle plate using processes can be Surface may beIJ11, IJ12, IJ17, graphic VLSI lithography and used fragile to the touchIJ18, IJ20, IJ22, processes etching. IJ24, IJ27, IJ28, IJ29, IJ30, IJ31,IJ32, IJ33, IJ34, IJ36, IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44Monolithic, The nozzle plate is a High accuracy Requires long IJ03,IJ05, IJ06, etched buried etch stop in the (<1 μm) etch times IJ07,IJ08, IJ09, through wafer. Nozzle Monolithic Requires a IJ10, IJ13,IJ14, substrate chambers are etched in Low cost support wafer IJ15,IJ16, IJ19, the front of the wafer, No differential IJ21, IJ23, IJ25,and the wafer is expansion IJ26 thinned from the back side. Nozzles arethen etched in the etch stop layer. No nozzle Various methods have Nonozzles to Difficult to Ricoh 1995 plate been tried to eliminate becomeclogged control drop Sekiya et al the nozzles entirely, to positionaccurately U.S. Pat. No. 5,412,413 prevent nozzle Crosstalk 1993Hadimioglu clogging. These problems et al EUP 550,192 include thermalbubble 1993 Elrod et al mechanisms and EUP 572,220 acoustic lensmechanisms Trough Each drop ejector has Reduced Drop firing IJ35 atrough through manufacturing direction is sensitive which a paddlemoves. complexity to wicking. There is no nozzle Monolithic plate.Nozzle slit The elimination of No nozzles to Difficult to 1989 Saito etal instead of nozzle holes and become clogged control drop U.S. Pat. No.4,799,068 individual replacement by a slit position accurately nozzlesencompassing many Crosstalk actuator positions problems reduces nozzleclogging, but increases crosstalk due to ink surface waves

[0087] DROP EJECTION DIRECTION Description Advantages DisadvantagesExamples Edge Ink flow is along the Simple Nozzles limited CanonBubblejet (‘edge surface of the chip, construction to edge 1979 Endo etal GB shooter’) and ink drops are No silicon High resolution patent2,007,162 ejected from the chip etching required is difficult Xeroxheater-in- edge. Good heat Fast color pit 1990 Hawkins et al sinking viasubstrate printing requires U.S. Pat. No. 4,899,181 Mechanically oneprint head per Tone-jet strong color Ease of chip handing Surface Inkflow is along the No bulk silicon Maximum ink Hewlett-Packard (‘roofsurface of the chip, etching required flow is severely TIJ 1982 Vaughtet al shooter’) and ink drops are Silicon can make restricted U.S. Pat.No. 4,490,728 ejected from the chip an effective heat IJ02, IJ11, IJ12,surface, normal to the sink IJ20, IJ22 plane of the chip. Mechanicalstrength Through Ink flow is through the High ink flow Requires bulkSilverbrook, EP chip, chip, and ink drops are Suitable for siliconetching 0771 658 A2 and forward ejected from the front pagewidth printrelated patent (‘up surface of the chip. heads applications shooter’)High nozzle IJ04, IJ17, IJ18, packing density IJ24, IJ27-IJ45 thereforelow manufacturing cost Through Ink flow is through the High ink flowRequires wafer IJ01, IJ03, IJ05, chip, chip, and ink drops are Suitablefor thinning IJ06, IJ07, IJ08, reverse ejected from the rear pagewidthprint Requires special IJ09, IJ10, IJ13, (‘down surface of the chip.heads handling during IJ14, IJ15, IJ16, shooter’) High nozzlemanufacture IJ19, IJ21, IJ23, packing density IJ25, IJ26 therefore lowmanufacturing cost Through Ink flow is through the Suitable forPagewidth print Epson Stylus actuator actuator, which is notpiezoelectric print heads require Tektronix hot fabricated as part ofheads several thousand melt piezoelectric the same substrate asconnections to drive ink jets the drive transistors. circuits Cannot bemanufactured in standard CMOS fabs Complex assembly required

[0088] INK TYPE Description Advantages Disadvantages Examples Aqueous,Water based ink which Environmentally Slow drying Most existing ink dyetypically contains: friendly Corrosive jets water, dye, surfactant, Noodor Bleeds on paper All IJ series ink humectant, and May jets biocide.strikethrough Silverbrook, EP Modern ink dyes have Cockles paper 0771658 A2 and high water-fastness, related patent light fastnessapplications Aqueous, Water based ink which Environmentally Slow dryingIJ02, IJ04, IJ21, pigment typically contains: friendly Corrosive IJ26,IJ27, IJ30 water, pigment, No odor Pigment may Silverbrook, EPsurfactant, humectant, Reduced bleed clog nozzles 0771 658 A2 and andbiocide. Reduced wicking Pigment may related patent Pigments have anReduced clog actuator applications advantage in reduced strikethroughmechanisms Piezoelectric ink- bleed, wicking and Cockles paper jetsstrikethrough. Thermal ink jets (with significant restrictions) MethylMEK is a highly Very fast drying Odorous All IJ series ink Ethylvolatile solvent used Prints on various Flammable jets Ketone forindustrial printing substrates such as (MEK) on difficult surfacesmetals and plastics such as aluminum cans. Alcohol Alcohol based inksFast drying Slight odor All IJ series ink (ethanol, 2- can be used wherethe Operates at sub- Flammable jets butanol, printer must operate atfreezing and others) temperatures below temperatures the freezing pointof Reduced paper water. An example of cockle this is in-camera Low costconsumer photographic printing. Phase The ink is solid at No dryingtime- High viscosity Tektronix hot change room temperature, and inkinstantly freezes Printed ink melt piezoelectric (hot melt) is melted inthe print on the print medium typically has a ink jets head beforejetting. Almost any print ‘waxy’ feel 1989 Nowak Hot melt inks aremedium can be used Printed pages U.S. Pat. No. usually wax based, Nopaper cockle may ‘block’ 4,820,346 with a melting point occurs Inktemperature All IJ series ink around 80° C. After No wicking may beabove the jets jetting the ink freezes occurs curie point of almostinstantly upon No bleed occurs permanent magnets contacting the print Nostrikethrough Ink heaters medium or a transfer occurs consume powerroller. Long warm-up time Oil Oil based inks are High solubility Highviscosity: All IJ series ink extensively used in medium for some this isa significant jets offset printing. They dyes limitation for use in haveadvantages in Does not cockle ink jets, which improved paper usuallyrequire a characteristics on Does not wick low viscosity. Some paper(especially no through paper short chain and wicking or cockle).multi-branched oils Oil soluble dies and have a sufficiently pigmentsare required. low viscosity. Slow drying Micro- A microemulsion is aStops ink bleed Viscosity higher All IJ series ink emulsion stable, selfforming High dye than water jets emulsion of oil, water, solubility Costis slightly and surfactant. The Water, oil, and higher than watercharacteristic drop size amphiphilic soluble based ink is less than 100nm, dies can be used High surfactant and is determined by Can stabilizeconcentration the preferred curvature pigment required (around of thesurfactant. suspensions 5%)

1 An inkjet nozzle arrangement comprising: a nozzle chamber having afluid ejection port defined in one surface of the chamber; a paddle vanelocated within the chamber, the paddle vane being adapted to be actuatedby a thermal actuator for the ejection of fluid out of the chamber viathe fluid ejection port; a thermal actuator located externally of thenozzle chamber and attached to the paddle vane, wherein the thermalactuator includes a plurality of separate spaced apart elongate thermalactuator units, which are interconnected at a first end to a substrateand at a second end to a rigid strut member. 2 delete 3 (as amended) Anink jet nozzle arrangement as claimed in claim 1 wherein the rigid strutmember is connected to a lever arm having one end attached to the paddlevane. 4 (as amended) An ink jet nozzle arrangement as claimed in claim 1wherein the thermal actuator units operate upon conductive heating alonga conductive trace, the conductive heating including generation of asubstantial portion of the heat in an area adjacent the first end ofeach thermal actuator unit.
 5. An ink jet nozzle arrangement as claimedin claim 4 wherein said conductive heating includes a thinnedcross-section adjacent said first end. 6 (as amended) An ink jet nozzlearrangement as claimed in claim 1 wherein the thermal actuator unitscomprise conductive heating layers which, in turn, comprisesubstantially either a copper nickel alloy or titanium nitride. 7 (asamended) An ink jet nozzle arrangement as claimed in claim 1 wherein thepaddle vane is constructed from a similar conductive material toportions of the thermal actuator units and is conductively insulatedfrom the thermal actuator units. 8 (as amended) An ink jet nozzlearrangement as claimed in claim 1 wherein the thermal actuator units areconstructed from multiple layers utilizing a single mask to etch themultiple layers.
 9. An ink jet nozzle arrangement as claimed in claim 1wherein said nozzle chamber includes an actuator access port in a secondsurface of said chamber.
 10. An ink jet nozzle arrangement as claimed inclaim 9 wherein said access port comprises a slot in a corner of saidchamber and said actuator is able to move in an arc through said slot.11. An ink jet nozzle arrangement as claimed in claim 10 wherein saidactuator includes an end portion which mates substantially with a wallof said chamber at substantially right angles to said paddle vane. 12.An ink jet nozzle arrangement as claimed in claim 1 wherein said paddlevane includes a depressed portion substantially opposite said fluidejection port.
 13. A thermal actuator including a series of lever armsattached at one end to a substrate, said thermal actuator beingoperational as a result of conductive heating of a conductive trace,said conductive trace including a thinned cross-section substantiallyadjacent said attachment to said substrate.